Make WaitL1 and WaitL2 separate functions

[joshklop]

It is preferable to have receivers, rather than fields that are set when the struct is built.

monomer/e2e/stack.go

Lines 294 to 299 in 6e976af

	WaitL1: func(numBlocks int) error {
	return wait(numBlocks, 1)
	},
	WaitL2: func(numBlocks int) error {
	return wait(numBlocks, 2)
	},

If I'm missing the reasoning, please correct me @NiloCK.

[NiloCK]

On first write, they were separate but identical functions, which I combined as a de-duplication.

I'm fine either way, but it's a trade of indirection vs duplication with probably not a lot of gain in either direction.

[joshklop]

The best way to go is probably to have a single function in stack_test.go

func wait(client BlockByNumberInterface, numBlocks uint64) error {
    // implementation ...
}